Objective: To analyze methodological bias and variation of systematic reviews on diagnostic test accuracy (DTA).
Methods: Meta-analyses on DTA were identified through an electronic search through databases as Medline, Embase and Cochrane between 1 January 2008 and 31 December 2012. Results from Meta-analyses on 10 primary studies were included. Pairs of reviewers worked independently to extract the related data of interest, together with those original data of the primary studies. Mixed linear model was used to investigate the direction and strength of the association among the 14 studies, featuring on estimates of the diagnostic accuracy.
Results: A total of 23 papers on Meta-analyses with 550 primary studies were included. Results from mixed linear model showed that significant low estimates of diagnostic accuracy in studies unsatisfying " the reference standard would likely to correctly classify the target condition" [relative diagnostic odds ration (RDOR) =0.018 6, 95% CI: 0.001 0-0.358 5]. Studies whose reference standard were not independent of the index test produced significantly higher estimates of diagnostic accuracy (RDOR= 2.396 6, 95% CI:1.242 8-4.622 7).
Conclusion: Messages as " Is the reference standard likely to correctly classify the target condition?" and " Was the reference standard independent of the index test", were the origin of the methodological bias and variation of systematic reviews on diagnostic test accuracy.